In carrying out production of an oil well, wherein a pumpjack apparatus reciprocates a downhole pump device, the production zone often contains paraffinic hydrocarbons. The hydrocarbon zone usually is at an elevated temperature; and therefore, the paraffinic fraction of the liquid hydrocarbons are dissolved within the production fluid. As the production fluid is pumped uphole toward the surface of the ground, the temperature of the surrounding strata diminishes, especially when an aquifier near the surface of the earth is encountered. This produces a temperature gradient in the flowing production fluid. The reduction in temperature crystallizes the waxy or paraffinic material, and the paraffin commences to accumulate within a marginal length of the production tubing until the production rate diminishes to an unsatisfactory flow rate. In order to eliminate the deposition of the crystallized paraffin, various treatment fluids are sometimes introduced into the casing annulus. Still others have gone to great expense to install scraper devices on the sucker rod so that the deposited paraffin is mechanically scraped from the interior side wall of the production tubing. Still others have pumped treatment fluid downhole through the production string, through a bypass valve, into the casing annulus, thereby dissolving the paraffin deposits.
Installation of a bypass valve downhole in a borehole is limited by the design and construction of the biasing forces which cause the valve to remain in a closed configuration until a predetermined hydrostatic head is encountered to move the valve to the open position. Inasmuch as limited space is available, this expedient has heretofore been limited to very low pressure ranges which usually are unsuitable for hydrostatic heads encountered in most hydrocarbon producing wells.
Accordingly, it is desirable to be able to install a valve means downhill in a borehole wherein the valve means has associated therewith a novel valve construction which remains closed under an extremely high hydrostatic pressure, and which is able to be opened when still a greater pressure is artificially applied to the tubing string.